Abstract
Drilling an ultra-deep hole in an intact portion of oceanic lithosphere, through the crust to the Mohorovičić discontinuity (the ‘Moho'), and into the uppermost mantle is along-standing ambition of scientific ocean drilling (Bascom,1961; Shor, 1985; Ildefonse et al., 2007). It remains essential to answer fundamental questions about the dynamics of the Earth and global elemental cycles. The global system of mid-ocean ridges and the new oceanic lithosphere formed at these spreading centers are the principal pathways for energy and mass exchange between the Earth's interior, hydrosphere, and biosphere. Bio-geochemical reactions between the oceans and oceanic crust continue from ridge to subduction zone, and the physical and chemical changes to the ocean lithosphere provide inventories of these thermal, chemical, and biological exchanges.